FAMILY PLOT seems to get either overlooked or a "meh" reaction. Then again when the other movies on your directing resume include PSYCHO, REAR WINDOW, VERTIGO, NORTH BY NORTHWEST, etc. etc. it's got pretty big shoes to fill.
The last of Hitchcock's features, it has a pleasant tongue-in-cheek quality that makes it amusing and enjoyable - especially after the tedious political thrillers of TOPAZ and TORN CURTAIN, and the very dark FRENZY. It may not be up to the standards of the director's more famous works, but it's worth checking out.